Negative turned postive

Took a pregnancy test last night just BC I have that feeling when you just know there's something off. Plus some physical symptoms, twitching and swimming feeling in abdomen, dark areolas, some discharge. I had my period like 2 and a half weeks ago and I should just be barely ovulating. Anyway I took a generic test and it was negative. Left it out and in the morning it was positive. We're not trying to conceive but if it happens it happens. We have a 2 year old and when I took the test for him, the positive line happened right away and it was super dark. Just wondering if anyway else had this experience and it turned out you were pregnant after all.